A structure of the process cartridge is known in which it is demountable, in a predetermined direction substantially perpendicular to a rotational axis of the image bearing member or the like, from the main assembly of the apparatus which is not provided with a mechanism for moving a main assembly side engaging portion (main assembly side coupling member) provided in the main assembly of the electrophotographic image forming apparatus to transmit a rotational force to a rotatable member such as the image bearing member, in the rotational axis direction, in interrelation with an opening and closing operation of a main assembly cover of the main assembly of the apparatus. In the structure, the coupling member of the process cartridge is engaged with the main assembly side engaging portion.
In such a coupling type (rotational force transmission means), it is known that the coupling member provided in the process cartridge is movable in the rotational axis direction, by which an engaging operation and a disengaging operation of the coupling member by a mounting and demounting operation of the process cartridge to the main assembly of the apparatus is made possible (Japanese Laid-open Patent Application No. 2009-134284).
It is also known that the coupling member provided on the process cartridge is made movable in the rotational axis direction, and is inclinable relative to the rotational axis, by which the engaging operation and the disengaging operation of the coupling member in interrelation with the mounting and demounting operation of the process cartridge relative to the main assembly of the apparatus is enabled (Japanese Patent 4498407).